Method of and System for Inducing a Planned Avalanche

ABSTRACT

A method and system for inducing a planned or controlled avalanche is disclosed. The system includes one or more sources of vibration mounted within a mass which is mounted within an aperture in the ground in the area where an avalanche has been determined to be likely to occur. One or more sensors is mounted between the source of vibration and the avalanche area (spaced from the vibration source), then the vibration source is operated at different frequencies to determine which frequency transmits the greatest force through the intervening terrain. Based on the analysis of the forces sensed at a distance from the vibration source, the best frequency for operation of the vibration source is determined and that frequency is used. Periodically, the process of testing the frequency versus force can be reviewed and the operating frequency adjusted. The present method and system envisions a plurality of vibrational sources arranged in a spaced array and uses more than one vibrational source to trigger a single avalanche at a desired time.

CROSS REFERENCE TO RELATED PATENT

The present patent application is a continuation-in-part of myco-pending patent application Ser. No. 13/176,723 filed Jul. 5, 2011 andentitled “AVALANCHE CONTROL SYSTEM AND METHOD”. The specification anddrawings of that patent application, which is sometimes referred toherein as the “First Avalanche Patent”, are specifically incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a method of (and system for) inducing aplanned (or controlled) avalanche in a region in which an uncontrolledavalanche of snow might occur. That is, a controlled avalanche may beinduced at a time which is most convenient and as frequently as desiredto avoid a large avalanche at an undesirable time.

2. Background Art

Ski slopes, roadways, housing and railways through canyons are at riskof an uncontrolled avalanche in some areas. An avalanche can occurspontaneously when a snow pack is unstable and there is enough verticalangle. Areas where the instability is the greatest are known asavalanche “birthing” areas

Naturally occurring avalanches are somewhat predictable, yet difficultto control. It is well known that earthquakes have caused several ofhistory's great avalanches. Snowmobile riding in an avalanche-prone areahas a propensity to initiate an avalanche, since the drive causesvibration which may make disturb the snow pack.

It is sometimes desirable to provide a controlled avalanche at a desiredtime in some situations. That is, it is desirable to have more, smalleravalanches than fewer, larger avalanches. Further, it may be desirableto have an avalanche at a time when few people or animals are present inthe area below an avalanche-prone area, for example, in the early hoursof a day while many are asleep or when ski facilities are not operating.Also, if the approximate time of a planned or controlled avalanche isknown, precautions can be taken for that time, such as closing ofroadway or trails in the affected areas or otherwise warning those whocould be in an area to avoid the area.

Various approaches have been suggested to induce a controlled avalancheto mitigate uncontrolled avalanche events. One approach to causing acontrolled avalanche has been to use a concussive event to trigger aplanned avalanche, for example, using artillery ordinance, dynamite or amortar shell. More recently, gas explosions in one of a variety of typeshave become popular to initiate an avalanche. For example, a fixedconcussive device igniting explosive gases is one such system for usinga gas explosion to initiate an avalanche, while a “Daisy Bell”concussive device carried by a helicopter is another such device whichcan initiate a controlled avalanche.

The use of ordinance, dynamite or a mortar shell requires specialhandling skills and storage and is the subject of increased regulationdue to safety concerns.

One must also consider that some systems for initiating a controlledavalanche do not work well during times of heavy snowfall, such as thosewhich require a helicopter. Operating a helicopter usually requires somevisibility of the surroundings, while a heavy snowfall obscures thevisibility of the pilot of the helicopter. So, in times when the risk ofan uncontrolled avalanche increases (during heavy snowfall), a controlsystem which uses a helicopter is less likely to be usable for thatpurpose.

Some of the systems of initiating a controlled avalanche are relativelycostly to use—for example, the Daisy Bell system requiring a helicopterand pilot.

Additionally, some of these prior art systems employ elements and/orcompounds which can be harmful to the environment, including the watersupply. Various materials contained in explosives are toxic to peopleand/or animal and tend to remain in the water supply long after atriggering of the explosive, polluting the water supply and causing harmto those who use the water supply, directly or indirectly. For example,many explosives include aromatic hydrocarbons such as toluene as acomponent (for example, TNT) and toluene is a long lasting materialwhich does not break down quickly and which is harmful to life, even inrelatively small doses. Some of these materials are relatively solublein water, while others are relatively insoluble in water, making theimpact on the environment hard to predict, either regarding theshort-term impact or the longer-term impact.

Accordingly, it will be appreciated that the prior art system forinducing an avalanche have undesirable disadvantages and limitations.

SUMMARY OF THE INVENTION

The present invention overcomes some of the disadvantages and limitationof the prior art systems for inducing a planned or controlled avalancheof snow in those areas which have been identified as prone to avalancheactivity.

The present invention allows for creating many small controlledavalanches to reduce the risk of a larger, uncontrolled andunpredictable avalanche.

The present invention would also appear to be “friendlier” to theenvironment in avoiding undesirable chemicals and inconveniently-timedavalanches which may jeopardize lives. Further, since an avalanche mayclose roadways and other accesses, it would be desirable to “schedule”such avalanches at a time which is convenient (like the dead of thenight), rather than allowing such events to occur naturally at aninconvenient time such as at a time of peak activity.

The present invention includes a method of setting up a vibrationalsystem to induce a controlled avalanche at a desired time.

The present invention also allows for the system to be tuned tocompensate for differences in the ground surrounding an avalanche-proneor avalanche birthing area. The tuning can also compensate forvariations in the attachment of one or more vibration-inducing sourceswith the surrounding ground.

The present system for inducing a controlled avalanche also appears tobe relatively inexpensive to use (and reuse) and provides a minimalenvironmental impact, especially compared with alternate systems forcreating an induced avalanche. This system also has the advantage thatit can be operated in almost any kind of weather, not being dependent onmoving people or equipment to the site of the desired avalanche.

Other objects and advantages of the present invention will be apparentto one of ordinary skill in the art in view of the following descriptionof the invention, taken in combination with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial representation or a perspective view of an area ofan avalanche-prone area, showing one arrangement of system for inducinga controlled avalanche including a vibration unit;

FIG. 2 is an enlarged view of a portion of FIG. 1, looking generallydownward on an avalanche prone area having a plurality of vibrationunits (or sources) mounted in an array;

FIG. 3 a cross sectional view of an system for creating vibration usedin the avalanche-prone area of FIGS. 1 and 2;

FIG. 4 is a flow chart of one process useful in the present invention;and

FIG. 5 is a cross sectional side view of one vibration unit useful inthe system of FIGS. 1 and 2; and

FIG. 6 s a top view of the vibration unit of FIG. 5, with its top coverremoved.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a pictorial representation of a mountainous area 10 inwhich avalanches can be expected. The mountainous area 10 includes aplurality of peaks 12, 14 and 16, with an avalanche origin region 20defined between the lines 14 a and 14 b delineating an avalanche-pronearea. The avalanche origin region 20 (sometimes alternatively called an“avalanche-birthing” or “avalanche-prone” area) often has a substantialterrain slope, perhaps averaging approximately 40 degrees, and islocated within a terrain area in which the slope of the terrain isgenerally more gentle. A plurality of vibration sources 30 are mountedwithin the avalanche prone area 20 in accordance with the presentinvention. These vibration sources 30 may be generally of the typedescribed in the First Avalanche Patent referred to above andincorporated herein by reference or use other similar systems forproducing vibration.

FIG. 2 shows an enlarged version of the avalanche-prone region 20between the lines 14 a and 14 b of FIG. 1. A plurality of vibrationsources 30 are indicated by the reference numerals 30 a through 30 j.Surrounding one of the vibration sources 30 a are a plurality ofvibration sensors 40 a, 40 b, 40 c and 40 d. Each of these vibrationsensors is an instrument which measures the movement of the groundnearby the sensor and may be an accelerometer or a seismic sensor of thetype used to detect, measure and locate earthquakes. Such accelerometersor seismic detectors are commercially available devices which arereadily available and provide a time-varying electric signalrepresentative of the displacement (or vibration) of the earth in theimmediate area.

FIG. 3 shows a flow chart of one method of using the vibration equipmentof the present invention. The process starts with the assembly of one ormore vibration units (as described later in this document) at block 110.Next, the one or more vibration units are installed in the ground atblock 120. This is accomplished by providing an aperture in the groundin the approximate shape of the cross section of the vibration units, alittle wider and deeper than the unit to allow it to fit in the groundconveniently with little clearance (and, as will be discussed later, thevibration unit(s) may be secured in place with an adhering material—suchas concrete or cement—to provide a better vibration-transmittingconnection between the vibration unit and the ground). While it isdesirable to have the top of the vibration units below the surface ofthe ground, it is also desirable to have the vibration units not buriedtoo deep in the ground to allow each vibration unit to vibrate the upperlayers of the adjacent ground and to transmit the vibrational forcesoutward to the extent possible, rather than downward (into the ground).At block 130 the next step is to calibrate at least one (or each) of thevibration units (see discussion below, especially in connection withFIG. 4). The vibration units can also be re-calibrated periodically toadjust for any changes in the units and/or the surrounding ground,perhaps as a result of ground changes, avalanches or belt tension or asa result of the seasonal weather cycles where the ground heats duringthe summer and cools during the winter, possibly changing thecharacteristics of the ground around the vibration unit. Thus, anoptional timer is set to provide set time for a recalibration of thevibration source(s), and block 135 checks to see whether it is time tore-calibrate the unit. Block 140 responds to a triggering signal totrigger an avalanche by turning on the vibration source (and shaking theground immediately around the vibration source). This triggering signalcan result from sensing the amount of snow nearby, from a visualindication (an observer noting an accumulation of snow in the area) orfrom a remote signal (perhaps in response to a sensing of snowfallexceeding a preset limit or a time when the avalanche has been set to betriggered).

FIG. 4 shows a representative plot the sensed ground vibration response(the output) as a function of the vibration frequency of the vibrationsource (the input). The sensors 40 a, 40 b, 40 c and 40 d shown in FIG.2 sense the effective ground vibration (or seismic activity) around thevibration source 30 a as the frequency of the vibration is altered, thenthe vibration versus frequency is plotted. Each of these sensors (suchas sensor 40 a) may be an accelerometer or other suitable seismicsensing device with a suitable output or record. This frequency ofvibration can be altered either manually (an operator changing the motorcontrols) or by an automatic stepping function, as desired. It isbelieved that FIG. 4 shows a representative plot for a typical groundsample in an avalanche-prone area 20. The plot 150 of operatingfrequency of the vibration source (along the x-axis) versus sensedvibration (along the y-axis) is shown in this view and includes arelative maximum 152 at f1 (where the vibration level is v1), anabsolute maximum f2 and another relative maximum f3. As shown in thisFIG. 4, a vibration response or level v1 is sensed at the frequency f1,the vibration response or level v2 at the frequency f2 and the vibrationresponse or level v3 at the frequency f3, with the vibration response orlevel v2 being the highest of those shown in this FIG. 4. Under thesecircumstances, the frequency f2 is chosen as the frequency where thegreatest vibration is transmitted through this particular groundconfiguration.

Of course, it may be easier (and more convenient as well as safer) tomeasure the ground response during periods of dry weather during a timewhen snow is not present—which would be a time when avalanches are notexpected because there's no snow present and the temperatures might bewarmer than those during the peak avalanche seasons. It is expected thatthe ground may have a different response to vibration based ontemperature and based on the presence of (or absence of) a pile of snow,and the frequency at which the ground is most responsive may requireadjustment for changes in temperature and ground loading. That is, thepeak response may shift as a result of the ground becoming colder and/orpiled with snow, and it may be desirable to compensate for changes insuch variables in setting the preferred rate of vibration. It is alsoanticipated that different ground characteristics, even in adjacentareas, may produce different ground characteristics, requiring differentfrequencies to be used for different vibration sources, even though thesources may be close to one another. Accordingly, it will be apparentthat the desirable operating frequency may be the observed bestfrequency with an offset to compensate for the temperature and for thesnow pack on the ground in some instances.

FIG. 5 is a cut-away side view of one vibration unit 30 useful in thepresent invention mounted within an aperture in the surrounding ground300. The vibration unit 30 includes a housing 210 to which legs 220mount a flywheel 230 using bearings 240. Drive belt 250 couples theflywheel 230 to a motor 260 which is mounted to the housing 210 bymounts 270. An optional tension device 255 keeps the drive belt 250taut. The motor 260 may generate heat and the assembly may be mounted ina location where the temperature varies depending on the time of year,so the belt 250 may need tightening over time or use, hence a tensiondevice 255 may be provided—and periodic replacement and/or adjustment ofthe drive belt 250 may be desirable.

The flywheel 230 is desirably asymmetric to produce vibration as itrotates. One way to achieve such asymmetry is to remove circularportions 230′ from one side of of the flywheel 230, making the side ofthe flywheel 230 with the removed material lighter than the side of theflywheel 230 on which no material has been removed. Another way tocreate asymmetry (or unbalance) in the flywheel 230 would be to mountweights on one side, making that side of the flywheel heavier than theside without the weights. Yet another way to create an asymmetricflywheel is to mount the flywheel 230 off center, so that one side ofthe flywheel is heavier than the other side.

The motor 260 may be a direct current motor operating at a relativelylow voltage, such as 24 volts. A 24 volt power supply can be obtainedthrough the use of two pair of 12 volt automotive batteries (or by othersuitable powering, such as wiring into a commercial electrical supply orthrough the use of photovoltaic cells deriving power from solar energywhich is then stored in batteries to be used when the sun is notshining). The motor 260 is one which can be driven at various speeds sothat the optimum speed can be determined during a set-up or calibrationperiod. That is, the motor 260 is operated at a range of differentfrequencies f1, f2, f3, . . . and the response of the ground in thevicinity is measured to determine which frequency provides the besttransmission of vibrational forces (as discussed above in connectionwith FIG. 4). That is, the ground 300 may have a differing response tovibrational forces at different frequencies, due to local differences inthe materials and/or the adhesiveness of the ground in the vicinity. Ifthe ground is very colluvial, it may be less transmissive of forces,including vibrational forces, than if the ground is more solid likegranite, and the peak transmissive force is likely to occur at adifferent operating frequency. It is desirable in this application todetermine the frequency at which the best transmission of vibrationalforces occurs for each vibrational source at the location where it issituated and then, if necessary, adjust for variations in temperatureand loading to determine the operating frequency for a controlledavalanche causing vibration and to induce the avalanche at a controlledtime.

The vibrational unit 30 has the housing 210 which may be a concreteculvert formed with a base which is either integral with it or securelyattached to it. A steel plate 200 may be provided to securely mount thelegs 220 and the motor 260 along with other components such as a batteryand electrical conduit. The electrical conduit may serve the functionsof signal transmission (to report the operating frequency, to set anoperating frequency or to provide a signal triggering an avalanche) andmay also serve as a power transmission function, either for providingprimary power (providing the main drive for the motor driving theflywheel) or for providing back-up power (to supplement the power storedin a battery and/or generated by the photovoltaic cells).

The top or upper portion of the vibration unit 30 is shown mountedapproximately flush with the surrounding ground 300. A cover 295 isshown atop the vibration unit to keep undesirable materials—soil andwater (such as snow) from filling the vibration unit 30. In addition,the lower portion of the housing 210 is provided with drain holes 290 toallow any water which enters the vibration unit 30 to drain from thevibration unit instead of accumulating and interfering with theoperation of the components, including the flywheel 230, motor 260 andthe included electrical system and components. Additional apertures (notshown) may also be provided to allow electrical conduits to enter thevibration unit, but such apertures would often be positioned above thebottom of the vibration unit 30 to minimize water problems.

The process of installing a vibration unit 30 in the ground 300generally includes the step of preparing an aperture in the ground 300slightly larger than the cross sectional shape of the vibrational unit30 and approximately as deep as the height of the vibration unit 30.Then the vibration unit 30 is inserted into the aperture. If there isclearance between the vibration unit 30 and the ground 300, thatclearance can be removed by filling the clearance with a suitableadhesive material, such as cement, shown by the reference numeral 292between the ground 300 and the vibration unit 30 in FIG. 5. Thisadhesive material 292 provides the advantages of securing the vibrationunit in place (so the vibration unit 30 less like to become dislodged,even in the event of an avalanche or water flow in the area) and toimprove the force-transmission characteristics from the vibration unit30 to the ground 300. The adhesive material 292 also can serve a sealingfunction, to keep water from accumulating within the aperture. While thevibration unit 30 does not have to be cylindrical in shape, it is shownas such in this example to allow for a circular hole to be used as theaperture in the ground 300. The circular shape also facilities use of aconcrete culvert to be used in the present invention, with such devicesbeing readily available and at a relatively low cost, since they aremass produced and widely used in other applications.

FIG. 6 shows a top view of the vibration unit 30 used in the presentinvention (with the top removed to view the contents). This viewsuggests the cylindrical shape of the vibration unit 30 in its preferredembodiment, given the round cross section of the wall or housing 210.Within the wall 210 are the motor 260 with the drive belt 250 andtension device 255 coupled to the belt 250, with the drive belt 250transmitting rotational force from the motor 260 to the flywheel 230.The flywheel 230 is mounted by its legs 220 to the base 200 and bearings240 are mounted to the flywheel 230.

Also shown in FIG. 6 is a battery (or power supply) 410 which consistsof two automotive 12 volt batteries connected in series to provideapproximately 24 volts. The voltage for the batteries and their powertype are chosen based on the requirements of the motor 260, which inthis case has been chosen as a 24 volt direct current motor. Of course,other types of motors 260 could be used to advantage in the presentinvention, and one might even use an alternating current motor ifalternating current was available, either through a connection to acommercial power grid or through the use of an inverter, convertingdirect current into alternating current.

Of course, many modifications are possible to the present inventionwithout departing from its spirit and some of the features described canbe used to advantage without the corresponding use of other features.While a preferred material of concrete has been discussed in connectionwith the foregoing example, there are many substitutes which could beused to advantage, including metals and alloys, if desired, including asteel housing (like a steel culvert). Some plastics may also be usablein the present invention. While the housing which has the vibratorysource mounted can be a single piece, it also could be formed ofmultiple pieces which are secured together. Further, those skilled inthe relevant art will appreciate that the present invention can beoperable without being at its greatest effectiveness. For example, thetuning of the present invention will disclose the responsiveness of thesoil to the vibrational forces applied, and it is possible to use aneffective frequency without using the optimum frequency. It is alsosuggested that the system be re-tuned at periodic intervals, such asannually, to compensate for changes in the soil and/or attachment orchanges in the operating characteristics of the vibrational source. Itmay be possible to predict the changes and adjust for the suspectedchanges in the operational characteristics without redoing the testing.Accordingly, it will be appreciated that the description of thepreferred embodiment is for the purpose of illustrating the principlesof the present invention and not in limitation thereof.

Having thus described the invention, what is claimed is:
 1. A method ofinducing a controlled avalanche in an area where snow has beendetermined to be likely to avalanche, the steps of the methodcomprising: mounting a source of vibration within the ground in the areawhere an avalanche is likely to occur; setting up the vibration sourceby operating it at different frequencies and determining a desirablefrequency based on the ground vibration detected at a distance from thesource of vibration; and operating the source of vibration at afrequency based on the determined desirable frequency when a controlledavalanche is desired in the area.
 2. A method of inducing a controlledavalanche including the steps of claim 1 and further including the stepof mounting a plurality of vibration sources in the area at spacedlocations.
 3. A method of inducing a controlled avalanche including thesteps of claim 2 and further including the step of setting one vibrationsource at one frequency and a different vibration source at anotherfrequency.
 4. A method of inducing a controlled avalanche including thesteps of claim 1 wherein the step of mounting the source of vibration inthe ground includes the step of securing a housing to the ground.
 5. Amethod of inducing a controlled avalanche including the steps of claim 4wherein the step of securing the source of vibration in the groundincludes the step of assembling a flywheel to a motor and mounting theassembled flywheel and motor to a housing.
 6. A method of inducing acontrolled avalanche including the steps of claim 5 wherein the step ofmounting the source of vibration includes the step of forming a roundhole and mounting the assembly in a cylindrical concrete member andinserting the cylindrical concrete member in the round hole.
 7. A methodof inducing a controlled avalanche including the steps of claim 6wherein the step of securing the source of vibration includes the stepof using cement to secure the concrete member in place.
 8. A method ofinducing a controlled avalanche including the steps of claim 1 whereinthe method further include the step of draining unwanted material from ahousing mounting the source of vibration.
 9. A method of inducing acontrolled avalanche including the steps of claim 1 further includingthe step of enclosing the source of vibration within a housing whichincludes a removable lid.
 10. A method of inducing a controlledavalanche including the steps of claim 1 wherein the step of determiningthe frequency at which the vibration source is to operate includesadjusting the frequency for the temperature.
 11. A method of inducing acontrolled avalanche including the steps of claim 1 wherein the methodincludes the steps of mounting a plurality of vibration units within asingle avalanche-prone area, determining an operating frequency for theplurality of vibration units and triggering the plurality of vibrationunits at about the same time to create a single controlled avalanche.12. A system for inducing a controlled avalanche in a portion of groundwhere an avalanche is likely to occur, the system comprising: a sourceof vibration mounted within the ground including a drive systemoperating at different frequencies; means for varying the frequency ofoperation of the drive system for the source of vibration anddetermining at which frequency the ground has the greatest vibration;operating the source of vibration at a frequency based on the determinedfrequency at which the ground vibration is the greatest; and atriggering signal operating the source of vibration when a controlledavalanche is desired.
 13. An system including the elements of claim 12and further including a plurality of spaced vibration sources, where thetriggering signal operates the plurality of vibration sources to triggera controlled avalanche.
 14. An system of the type described in claim 12wherein the source of vibration includes an asymmetric flywheel.
 15. Ansystem of the type described in claim 12 wherein the source of vibrationis mounted within a concrete cylindrical housing.
 16. An system of thetype described in claim 12 wherein the vibration source includes aremovable top.
 17. An system of the type described in claim 12 whereinthe vibration source is mounted within a housing which resists intrusionof soil or water.
 18. An system of the type described in claim 12wherein the vibration unit includes a housing with at least one drainfor allowing unwanted stuff to drain from the housing of the vibrationsource.
 19. A system of the type described in claim 12 wherein thevibration source includes a flywheel where material has been removedfrom one portion to create an asymmetric flywheel which vibrates. Totrigger a controlled avalanche when the vibration unit is operated at afrequency which is likely to induce an avalanche.